Here are edited versions of the two paragraphs in "The Dream Animal" that served as the basis for the sentence combining exercise on page one.
Out of the Ice Age
From "The Dream Animal" by Loren Eiseley
The Ice Age was, particularly toward its close, a time of great extinctions. Some of the huge beasts whose intercontinental migrations had laid down the first paths along which man had traveled, vanished totally from the earth.
Mammoths, [which were] the temperate zone elephants, dropped the last of their heavy tusks along the receding fringes of the ice. The long-horned bisons upon whose herds man had nourished himself for many a long century of wanderings, faded back into the past. The ape whose cultural remnants at the beginning of the first glaciation can scarcely be distinguished from chance bits of stone has, by the ending of the fourth ice, become an artist, a world rover, and penetrator of the five continents.
There is nothing quite like this event in all the time that went before. The end of brute animal dominance had come at last.